I have just got a second hand iMac (Core 2 Duo 2.4 20" Mid 2007) Which has been fully wiped. I have connected it to wifi and am trying to install OS X by using the reinstall option but when I log in to the App Store it just says item temporarily unavailable. It seems to have decided that El Capitan 10.11 is what its looking for but cannot access it to download it.
Any suggestions so that I can get an OS on to this computer and actually use it?!
Thanks.
Best Answer
I have a 2007 iMac. A while back, I replaced the internal drive with a 1 TB hard disk. The Mac still has a working optical drive. Currently, the mac has 64 bit Windows 10 Pro, Ubuntu Linux, Yosemite and El Capitan installed. I am fortunate, in that I have a 2011 iMac running High Sierra and a Snow Leopard DVD.
One path to reinstall would be to install Snow Leopard from a DVD. Apple still sells the DVD for 20 USD. If necessary, you should upgrade to OS X 10.6.8. One way to accomplish this would be to download the Mac OS X 10.6.8 Update Combo v1.1. Finally, the current instructions for upgrading to El Capitan can be found here. This site has a this link to the Apps Store where El Capitan can be downloaded.
Another path would be find someone who has purchased (for free) El Capitan. If this person has access to a Mac running High Sierra or earlier, then they can download El Capitan to this Mac. El Capitan can be transferred to a bootable USB flash drive installer. The instruction are given here. Basically, the command below needs to be executed on a flash drive formatted
Mac OS Extended (Journaled)
with the label (Name)MyVolume
.Update: How to Get and Verify a Snow Leopard ISO File from the Internet
Mac User posted in an answer which states a Snow Leopard ISO file can be download from this website. This site shows an image of a DVD. I happen to have that very DVD. This is OS X version 10.6. So I decided to conduct some research using an iMac (21.5-inch, Mid 2011) running macOS High Sierra Version 10.13.6. Here is the work and results.
First, I downloaded the ISO file from the website. This was named
snow leopard install.iso
.Next, I used the Disk Utility to create a
DVD/CD master
image of the Snow Leopard DVD namedSnowLeopardDVD.cdr
. I used the commandshasum -a 256 snow\ leopard\ install.iso
to get a SHA256 checksum, as shown below.The command
ls -l SnowLeopardDVD.cdr snow\ leopard\ install.iso
produced the following output.This shows the download to be 24576 bytes larger. I used the
hexdump -C -s 7771496448 snow\ leopard\ install.iso
to display these extra bytes. The output shown below. This output shows all these extra bytes are zero.Next, I used the Finder application to mount both files. The
snow leopard install.iso
file mounted asdisk1
and theSnowLeopardDVD.cdr
file mounted asdisk3
. Neither of the next two commands produced any output. This means thedisk1
anddisk3
are identical to the files that were mounted.The output from
diskutil list disk1
anddiskutil list disk3
is shown below. The output shows the partitions are the same type and size.None of the commands shown below produced any output. This means the partitions are identical.
Next, I execute the command
cmp -l SnowLeopardDVD.cdr snow\ leopard\ install.iso
. Only the first and last 2 lines of the output is shown below.Since I now know both files are using the
Apple_partition_scheme
, I can post the output from the commandspdisk -lr /dev/disk1
and pdisk -lr /dev/disk3
, as shown below. Again the partitions appear to be the same type and size.Since I now know the block size is 2048 bytes, I can convert the byte counts given as output from the last
cmp
command to blocks, as shown below.The above conversion shows all the differences occur in the one unused 2048 byte block between the
Apple_Driver_ATAPI
andApple_HFS
partitions.The next commands extend the
SnowLeopardDVD.cdr
file by 24576 bytes of zeros. The following command zeros the 2048 byte block between theApple_Driver_ATAPI
andApple_HFS
partitions in thenSnowLeopardDVD.cdr
file.The command given below produces no output, thus confirming the
SnowLeopardDVD.cdr
andsnow leopard install.iso
files are now the same.The result of this research is outlined below.
The ISO I download is authentic. The differences that occur outside the partitions are not used and are zero in the ISO file.
If another website promotes the download of an ISO file of this same DVD, you can use the information in this answer to verify if the download is authentic. This is why I included the SHA256 checksum of the ISO file I downloaded.